1. Field of the Invention
This invention relates to an improved applicator for tape material having a heat-activatable adhesive and in one aspect to an improved device for activating the heat-activatable adhesive just prior to the application of cut lengths of tape to a receptor surface.
2. Description of the Prior Art
Dispensers for tape products and for applying discrete lengths of tape to articles are well known. Pressure-sensitive adhesive tape can be applied by advancing a section of the tape, cutting the section of tape and supporting the section of tape on a pad to advance the cut section of tape to an article to which it is to be applied. Examples of such dispensers are shown in U.S. Letters Pat. No. 3,472,724, issued Oct. 14, 1969 to J. H. Casey, and U.S. Letters Pat. No. 3,081,815 to J. W. Toensing, issued Mar. 19, 1963. Many other similar dispensers for pressure-sensitive tape are well known. In these devices however the cut section of tape is easily supported by vacuum since the backing for the tape is smooth and generally nonporous. A small amount of subatmospheric pressure will be sufficient to maintain the tape firmly against the pad during movement for application.
Dispensers are also known for dispensing lengths of a heat-activatable adhesive tape, by advancing the tape, cutting a discrete length from the strip of tape, preheating the adhesive on the tape to activate the same and applying the tape against a surface. Examples of such devices are known in the bookbinding art. One example is U.S. Letters Pat. No. 3,715,260 of P. L. Dornemann et al., issued Feb. 6, 1973. In this device a strip of tape is advanced from a supply roll, it is cut from the roll, a heater is passed over the adhesive in spaced relationship to activate the same by radiant heating, and then the edge of the sheets to be bound is moved into contact with the adhesive on the tape and forced thereagainst until the adhesive again cools. The tape utilized is a flexible sheet material capable of withstanding heat. The tape is also generally structured such that it can be supported or moved by a pneumatic member such as in the above-mentioned pressure-sensitive adhesive tape applicators. An example of an applicator for bookbinding tape using pneumatics is U.S. Letters Pat. No. 2,646,104 of T. B. Hawkes, issued July 21, 1953.
Conductive heating of heat-activatable adhesives by contacting the adhesive with the heating element is known, e.g., U.S. Letters Pat. No. 2,946,281, of A. O. Sohn, issued July 26, 1960, but obtaining rapid controlled heating by assuring brief intimate contact between the adhesive coating and the high temperature heater is not known.
Known systems which do not use pneumatics to support the tape are also known and one example is shown in U.S. Letters Pat. No. 3,625,799, of D. G. Way, issued Dec. 7, 1971. In this dispensing device the cut length of tape is retained on the applicating pad by means of anchoring pins which extend from the surface of the pad and perforate the cut section of tape. The anchoring pins move vertically out of their holding position when the face of the applicating pad comes into engagement with the surface to which the tape section is to be applied. This system does not fully support the strip of tape and the projecting pins would not allow the adhesive surface to be contacted other than with the article to which it is to be applied.
Therefore, the problem exists in being able to suitably support the cut length of tape having on one side of the tape backing a heat-activatable adhesive such that the adhesive surface could be moved past and into contact with a heating member to activate the adhesive to the desired depth without softening or deleteriously effecting the tape backing.